Finding genes

Many of the genes found by scientists so far are those involved in genetic conditions, such as cystic fibrosis - a lung disease, and Duchenne muscular dystrophy - a muscle-wasting disease. Genetic conditions are usually caused by a faulty version of a single gene and most are very rare. But genes are also involved in many common illnesses like asthma, diabetes and heart disease. Medical researchers are trying to identify these genetic influences and work out how they interact with other factors such as diet and lifestyle.

Some of the genes for genetic conditions that have been found on chromosome 4.